Abstract: In a GPS or similar radionavigation signal, a pair of coarse/acquisition signals are located at, near or toward the nulls of the precision/encrypted codes in the L1 band, the L2 band or both. The resulting difference in frequency provides a very wide lane capability. The existing centered coarse/acquisition signal can be retained for legacy purposes. When a receiver receives such signals, it first determines position (speed, time, attitude, etc.) in accordance with the signals having the smallest frequency difference and thus the widest lane and then proceeds to each narrower lane to refine the accuracy of the determination.

Abstract: A process for obtaining traffic situation data in a compressed form, while largely maintaining the reliability of the data, whereby a speed profile for a vehicle that moves in traffic and belongs to a sampling vehicle fleet ("floating car") is found and transmitted wirelessly to a traffic center from time to time. The has the following features:a) The current speed of the vehicle is found continually in the vehicle.b) In the vehicle, characterizing numbers that characterize discrete segments of the vehicle speed profile are found from the current speed values, which characterizing numbers are characteristic of the curve of the speed actually travelled in the given segment.c) The discrete segments of the speed profile are formed continuously during the vehicle trip, in that the end of a current segment, and thus the beginning of a new segment, is defined on the basis of the results of a comparison between the speed profile of the vehicle and the speed profile of at least one virtual reference vehicle.

Abstract: A vehicular traffic sensor capable of measuring traffic speed and volume in all weather conditions and at a low installed cost. The sensor makes use of multi-path interference of ambient radio frequency (RF) signals. The ambient RF signals can be, for example, control signals constantly transmitted by cellular telephone base stations. As vehicles travel along the roadway, they reflect RF signals in all directions. An antenna mounted near the side of the road will detect signals from the transmitter and signals reflected off the vehicle. Variations in the amplitude of the combination of the two signals can be processed using a method that allows the sensor to determine traffic speed and volume. This information can then be sent directly to a traffic management center. This provides an inexpensive sensor for wide-area traffic monitoring.

Abstract: A speed conversion coefficient calculating section 104 calculates a ratio of a GPS Doppler velocity calculated by a GPS velocity calculating section 101 to a vehicle speed measured by a speed sensor 102, thereby obtaining a speed conversion coefficient. There are provided a plurality of filtering sections 105-108 for averaging momently produced speed conversion coefficients. A filter selecting section 109 selects an optimum filtering section among these filtering sections 105-108. If a ratio of the speed conversion coefficient resultant from the speed conversion coefficient calculating section 104 to a presently adopted speed conversion coefficient is not within a predetermined range, an abnormality detecting & initializing section 110 notifies abnormality and initializes calculation process of the speed conversion coefficient in response to detection of such an abnormality.

Abstract: A travel velocity detector is installed in a mobile telephone station such as a portable telephone or a car telephone. The travel velocity detector adapts a received power level to a travel velocity of the mobile station. Two receiving circuits receive communication waves via respective antennas and output respective power levels E1 and E2 therefrom. The detected powers E1 and E2 are compared with each other to determine which of the powers is greater. A variation of the comparison result is then detected. The number of detected variations, corresponding to a switching frequency, is then counted during a preset time period. A relative travel velocity between the mobile station and an opposite transmitting station is estimated on the basis of the number of the counted variations.

Abstract: A satellite tracking system, including a terrestrial transmitter, a plurality of terrestrial receivers, and a controller/analyzer, operates in two modes. In an active mode, the transmitter emits a tracking signal within a spread spectrum to a satellite and at least one of the receivers receives the signal retransmitted by the satellite. The controller/analyzer then determines the satellite position and velocity from the received signal. In a passive mode, at least two receivers each receive a signal transmitted from the satellite during normal operation and the controller/analyzer determines the satellite position and velocity from the received signals. The satellite position and velocity can be used to determine the position of an unknown transmitter that causes interference at the satellite.

Abstract: Communication devices and communication network techniques are employed to meet safety-critical, operational requirements for train location and control in railroad and public transit applications. On-board and trackside communication radios participate in a synchronous, time-slotted communication network, providing contentionless and highly responsive access to all participants. Encrypted, validated, and error protected communication links provide reliable and redundant transfer of information among the train, trackside, and control station radios. Spread spectrum communication techniques enable range measurements between all participants. These wireless communication links relay train range measurements to control or processing stations and relay control information (principally speed commands) from the processing stations to the trains. High resolution position location is determined along elevated, at-grade, and in-tunnel tracks using wireless methods and sparse device placement.

Abstract: A radio navigation system including:a means to determine, at a point (M.sub.1) of the trajectory of a moving body to be localized, the speed vector of said moving body and, possible, the "n" order derivatives of said speed vector (with n>1),a means to perform at least three successive measurements of distance, respective between a geodesic point at the ground and three successive positions (M.sub.1, M.sub.2, M.sub.3) of said moving body,a means to computer the position (M.sub.3) of said moving body by resolving a system of equations from the results thus obtained, expressed in one and the same reference system.

Abstract: A method for measuring the velocity (v) of a moving target (A). Radio signals are transmitted by means of radio transmitter-receiver arrangements of both the measuring station (B) and the target station (A) and received at the opposite stations (A,B), the frequencies of which signal include Doppler shifts (fd) to be observed both at the measuring station (B) and in the measuring target (A). On the basis of the Doppler shifts (fd), the escape and/or approach velocity (v) of the target to be measured is determined relative to the measuring station (B). Radio signals are transmitted from the measuring station (B) and the target station (A), the frequencies of which signals deviate from each other by a relatively small frequency difference (fk) or by a Doppler frequency shift (fd), the absolute value of which small frequency difference remains at least as high as the absolute value of the largest expectable Doppler frequency shift (fd.sub.max).

Abstract: In a global positioning system (GPS)/self-contained combination type navigation system for a vehicle, the GPS navigation data are received by the GPS antenna of the navigation system which are simultaneously transmitted from more than 3 pieces of satellites inclusively. From the GPS navigation data, GPS type velocity data is calculated, whereas self-contained type velocity data is calculated from self-contained type navigation data such as azimuth data and drive-distance data of the vehicle. Only when a difference between the self-contained type velocity data and the GPS type velocity data exceeds a threshold velocity, the GPS type velocity data is voided so as to determine the present position of the vehicle.

Abstract: A position estimator for determining the position and velocity of a moving platform in cooperation with radio navigation aids is described incorporating an unbiased estimator, such as a least means square estimator, a biased estimator for determining the angle of inner section of the lines of position from the radio naviation aids for determining the liklihood of geometric dilution of precision (GDOP) and a switch for selecting the estimate of position and velocity from said biased estimator at first times and the unbiased estimator at second times. The invention overcomes the problem of accuracy degredation associated with a nearly collinear measurement geometry which causes the variance of the position estimates to be higly inflated.

Abstract: Windfinding apparatus is described in which receiver processing of the Global Positioning System (GPS) signals is without knowledge of the spread spectrum codes. The apparatus receiver ignores the bi-phase code and recovers the carrier frequency of all satellites in view of the receiving antenna. Two of these receivers are used in a windfinding system. One of the receivers is located on the ground at a known latitude and longitude. The other receiver is placed on a weather balloon sonde and launched into the atmosphere. A telemetry transmitter aboard the sonde transmits a signal that contains the GPS carrier frequency information to the ground-based telemetry receiver. The telemetry receiver output and the local codeless GPS receiver feed a set of tracking filters. The filtered signals are evaluated to obtain a measurement of the difference between the local GPS receiver carrier frequency and the sonde GPS receiver carrier frequency caused by the velocity of the sonde relative to the ground-based receiver (i.

Abstract: An improved positioning system for a vehicle is shown. In the system, when radio wave can be received from only one satellite, the current position of the vehicle is computed based on a pair of navigational data, which are brought by radio wave received at the current time and by radio wave received at an earlier time.

Abstract: A system for measuring the velocity of a spacecraft from a position onboard the spacecraft is disclosed. This system includes a radio wave receiver means for receiving pulse trains from a plurality of preselected pulsars. A velocity measuring unit located on the spacecraft measures the velocity of the spacecraft based on the Doppler shift of the pulse trains transmitted from each of the plurality of preselected pulsars.